(I've reviewed most of the businesses mentioned here on their respective TA pages)
My husband and I spent 5 great days in the St. Augustine/Anastasia Island area. We flew into JAX and rented a car early-ish, and got into St. Augustine around midday. We decided to park and walk around in the Old City for a while to kill some time before our hotel check-in. Our favorite place to park is the lot behind PizzaAlley's. It's pretty central to everything, and we could always find a space there. We walked around and window-shopped for a little while, and decided to eat lunch at Cafe del Hidalgo, which was a great decision. We had a wonderful lunch, but didn't have any room left for gelato, so decided we would definitely come back for that. After wandering around for a couple of hours, we drove down to the island to our hotel, Beacher's Lodge in Crescent Beach. After checking in, we went to Publix to stock up on groceries for the week, and spent the rest of the day relaxing by the pool. The next day we drove down to check out Fort Matanzas, which was really fun (and free!). We spent about 3 hours there between touring the fort, wandering along the nature walk, and playing on possibly the world's most climbable trees. After the fort, we went back to our hotel for lunch, and spent the rest of the day hanging out on the beach. For dinner, we went back to the Old City, and ate at A1A Alehouse. Over the next few days, we went mini golfing at a couple of different places (the one next to the beach is definitely the best one), wandered into little antique shops, and did finally make it back to the Cafe del Hidalgo for their delicious gelato. We had dinner at the South Beach Grill, which was great. Mostly, we hung out on the beach and by the pool. The weather this time of year is just perfect. It never got too hot, but was definitely warm enough for swimming and sunbathing. there were a few thunderstorms, but they just cooled everything off for a while. We took some beautiful drives along A1A, and walked around both the Old City, and along various beaches. We fished off the St. Augustine Pier, and watched locals cast net fish off the Matanzas Inlet bridge at sunset.
There are always tons of things do in this area, and we've been here a few times already, but there are always things we plan on doing on future visits. For example, we still haven't had a chance to do all the indoor tours in the Old City, like the Lightner Museum, the college, etc. We'll get to it, on one of our future trips :)